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From frederic barachant <ms.barach...@free.fr>
Subject Re: out of memory when writing blobs
Date Thu, 15 Mar 2007 09:09:42 GMT
Anders.
Thank you for your tests and your time.
At that moment, i have no possiblility to check more on that issue. My 
deadline is coming and i will not be afforded to pass more time on this.
Moreover, as lazy loading of blob is not possible from JPA/toplink, i 
will have to resort to loading by hand and thus will be able to use 
stream writing. As i checked that this way did not cause me problems i 
will follow it.
Thanks again.

Anders Morken a écrit :
>> PS. My small, slightly modified test case based on yours, successfully
>> churned through >1500 iterations of 6MB blob insertion with Derby
>> 10.2.2.0 in the classpath and a 100 page page cache while I wrote this
>> email. I moved the prepareStatement outside the loop, replaced your
>> copy/paste with a single while(true) {...} and added a counter to count
>> the number of loops but it's otherwise cut-and-pasted from what you
>> sent. 
>>     
>
> Just slightly related - a 1000-page page cache bombs after 5 iterations,
> a 500-page page cache seems to survive at least 100 iterations, a
> 750-page cache also survives at least 200 iterations.
>
> When taking a look at the heap dump (produced by giving Java the
> -XX:+HeapDumpOnOutOfMemoryError parameter on a 1000-page run and then
> waiting for the expected crash) using jhat, I can't find any other big
> memory eaters than the page cache. In total the cache manager referenced
> about 50MB of heap when Java died.  That includes every object reachable
> from the page objects in the cache, so it's not really the "size of the
> cache", but... 
>
> Well, at least it indicates that you can't just multiply the page cache
> size by the page size (Seemed to be 32K in this case - at least that was
> the size of the page data byte arrays) to find how much memory the cache
> is referring. =)
>
>   


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